Manhole closure



W. H. CAHALL MANHOLE GLOSURE Filed Oct. 29, 1951 www IN ENTL T TURA/EYE.

Patented May 1, 1934 i PATENr orrics MANHOLE CLOSURE William H. Cahall, Los Angeles, Calif., assignor to National Tank and Manufacturing Co., Los

Angeles, Calif., a corporation of California Application October 29,

Claims.

This invention relates to improvements in manhole closures and relates particularly to manhole constructions such as are employed on truck tanks and the like which transport gasoline and other highly inflammable fluids.

In this service there is considerable re hazard and an object of the invention is to provide an improved manhole construction in which the lire hazard is greatly reduced. Broadly this is accomplished by preventing any metal part from striking other metal parts in the act of opening or closing the manhole cover. If the parts were permitted to come in contact, sparks might be generated which are sufficient to ignite the highly inflammable liquid or vapors issuing therefrom.

Another object of the invention is to provide a manhole construction which is of simple and durable design and which providesY a substantially gas tight seal between the manhole cover and the seat provided therefor about the manhole and which has moving parts eifectively protected by a non-inammable cushioning material to prevent generation of sparks.

With the foregoing and other objects in view, which will be made manifest in the following detailed description, and specifically pointed out in the appended claims, reference is had to the accompanying drawing for an illustrative embodiment of the invention, wherein:

Fig. l is a partial View in top plan elevation, illustrating the dome of a truck tank having the manhole construction embodying the invention applied thereto.

Fig. 2 is a vertical section taken substantially upon the line 2 2 upon Figure 1.

Fig. 3 is a vertical section taken substantially upon the line 3 3 upon Figure 1.

Referring to the accompanying drawing, wherein similar reference characters designate similar parts throughout, the body of the tank is generally designated at l0, which usually has the conventional upstanding dome 11 in which there is formed a manhole l2. The cover construction has been illustrated as having been applied to this dome for the reason that the use of the dome is conventional practice upon truck tanks and the like but it will be readily appreciated that the application of the invention is not restricted to use upon domes. Surrounding the manhole 12 the dome 1l is bent downwardly and upwardly to form an annular groove 13 which contains a noninflammable compressible material 14. This material is preferably braided asbestos, although any equivalent material which will serve as a cushion and provide a yieldable seat for the edges of the 1931, Serial No. 571,799

cover 15 may be employed. On one side of the manhole there is secured a member 16 having upstanding ears 17. A hinge pin 18 extends through the ears and through the downwardly extending legs 19 of an inverted U shaped member 20. The hinge pin, which may be formed of steel, is preferably formed of a non-ferrous metal such as aluminum, brass, duralumin, which materially reduces the possibility of sparking when the cover 15 is being opened or closed. Asbestos washers 21 are interposed between the ears 17 and the legs 19 and surround the hinge pin 18. These washers serve to avoid metal frictional contact between the parts. A bracket extends over the top of the cover l5, this bracket being of general Y shaped form. It is preferably formed of two pieces of channel iron, indicated at 22 and 23, which are secured to the legs 19. These pieces converge forwardly over the top of the cover and have their vforward ends secured together. The webs of the channel irons project a slight distance farther than the anges and are apertured as at 24 to receive a lock. A cross bar 25 connects the pieces and is internally threaded to receive a screw 26 having a handle 27 which has a swiveled connection at 28 with the cover. While the screw may also be formed of steel, it is preferably formed of a non-ferrous metal to reduce the possibility of sparking. The horizontal portion of part 2G has an asbestos bumper 29 secured thereto as by rivets 30. This bumper extends around the rear edge of the member so that when the bracket and cover are swung into open position as indicated by dotted lines on Figure 3, the bumper will engage the dome 11 and prevent metal to metal contact at this point, thus reducing the possibility of sparking. The bracket may be locked in closed position by means of a clevis or hasp 31 of inverted U shaped form, which is hingedly connected to ears 32 on the dome by a hinge pin 33. Asbestos washers 34 are interposed between the legs of the clevis or hasp and the ears 32 to reduce the possibility of sparking and, as a further precaution, while the hinge pin 33 may be made of steel it is preferably formed of a non-ferrous metal to reduce the possibility of sparking.

From the above described construction it will be appreciated that when the bracket is in the horizontal position shown and locked in this position by the clevis 31, that the cover may be tightened by the screw 26 to effect substantially a gas proof seal. When it is desired to open the manhole the cover is first loosened by reversely rotating the screw 26 and the clevis or hasp 31 is swung forwardly. The bracket and the manhole cover can then be swung out of the way as indicated by dotted lines on Figure 2. It will be readily appreciated from the above described construction that provision is made for preventing metal to metal contact taking place between the parts so as to prevent the possibility of sparks due to striking or to friction, thusreducing the fire hazard.

Various changes may be made in the details of" construction without departing from the spirit or scope of the invention as dened by the appended claims.

I claim:

l. In a tank construction, a metal dome having a substantially horizontal section with a depressed annular groove and a manhole opening inside of the groove, a non-inflammable compressible packing in the groove, a metal cover having a down-turned flange, the edge of the flange engaging the packing, a metal bracket having downwardly extending legs, means to hinge the legs to the dome, means cooperative withvthe bracket to press the edge of the cover into contact with the packing, said packing preventing the metal of the cover and the. metalof the dome from contacting, said legs being hinged-tov the domeby upwardlyextending metallicears, the hinge comprising a pintle pin formed of non-ferrous Inaterialextending through the ears and the legs of the bracket, and asbestos washers on the pinbetween the ears and the legs.

2. In a tank construction, a metal dome having a substantially horizontal section with a downwardly extending annular groove with a manhole opening inside of the groove, a non-inflammable compressible packing in the groove, a metal cover having a down-turned flange, the flange bearing. on said packing, a bracket havingan inverted U-shapedmember with legs and with bars attached thereto to extend across the cover, the dome having ears, a non-ferrous pintle pin extending through the ears and the legs, asbestos Washers between the ears and the legs, a clevis hinged to the dome on the side opposite the ears, said clevis engaging an end of the bracket, and means on the bracket to press the cover into a sealing engagement with the packing.

3. In a tank construction as claimed in claim 2, the clevis having a non-ferrous pin forming the pivot to the dome, and washers on said pivot pin separating the clevis from the hinge element attached tothe dome.

, 4. In a tank. constructionv as claimed in claim 2, the means to press the cover comprising a nonferrous screw attached to the bracket, said screw having a screwing engagement with the cover.

5. In` av tank construction as claimed in. claim 2, the U-shaped member having an.l asbestos bumper attached thereto betweenthe legs, said bumper being adapted to engage the dome'when the bracket is in upward position to remove the cover from the packing.

W. H. CAHAL'IL. 

